Etching is a process of chemically removing layers from a surface of a solid substrate using an etchant, such as an acid or a mordant. In an etching process, parts of the solid substrate can be protected from etching by a masking material which resists etching and is hereinafter referred to as the “masking layer”. Any pattern can be made on the surface of a substrate by etching and using a suitable masking layer. To this end, the solid substrate can be a single block of materials, such as a glass sheet or a thin film coated on a base substrate such as a thin film of silver coated on a glass, and the masking layer may cover the entire surface of the substrate except the parts which must be etched. To obtain desirable results from the etching, the masking layer need to adhere to the surface of the substrate; not to be detached easily from the surface of the substrate; and not to react with the etchant.
Masking layers such as photo-resist layers and vapor-phase deposited layers have been known and used in the art. The afore-mentioned masking layers, may be associated with issues such as only being deposited on clean substrates and in clean environments. In this method, the existence of any foreign material on the surface may alter the adhesion of the masking layer to the surface of the substrate. Furthermore, thin masking layers may easily detach from the substrate, if the substrate is subjected to bending or deformation, during or after the etching process, which may limit the minimum thickness of the masking layer. On the other hand, the masking layer cannot be deposited on non-flat surfaces which may limit the applications of the conventional etching methods to flat surfaces and, prohibit the usage of the etching method inside enclosed passages or 3D substrates. From another point of view, masking layers known in the art may need to undergo thermal procedures to solidify, and obtain suitable hydrophobicity and decrease residual stress. Therefore, the methods known in the art may be associated with time and cost issues, and there is a need in the art for a simple and low-cost masking layer.